Linear and Nonlinear Relationships Between Variables

How two things are related or the degree to which they are related is often a question in any area of research, including forensic psychology research. A researcher might ask these questions: To what degree are drug use and criminal recidivism related? Are mental illness and violence related? To what degree is an increase in police patrols related to a decrease in crime rates?

Each of these forensic psychology research questions can be addressed using a correlational design. Correlational designs help determine if there is a relationship between variables. The relationship may be positive, meaning there is a positive linear relationship between the two variables; the relationship may be negative, which means there is a weak or nonexistent linear relationship between the two variables; or, the relationship may be curvilinear, which means that at times there appears to be a relationship and at times there does not.

To prepare for this Discussion:

• Review Chapter 9 in your course text, Research Methods for the Behavioral Sciences. Pay attention to the descriptions and examples of linear and nonlinear relationships, positive and negative linear relationships, and curvilinear relationships.

• Consider how these relationships are determined and what impact each type of relationship may have on a researcher's ability to make predictions.

• Using the Walden Library, select and review two or three articles on criminal recidivism, violent crime, or domestic violence in which the variables have positive and negative linear relationships.

• Consider the implications if the variables had a curvilinear relationship instead.

With these thoughts in mind:

Post by Day 4 a description of two variables that have a positive linear relationship and two variables that have a negative linear relationship in the research articles you reviewed. Then, explain the implications on the studies if each of those variables had a curvilinear relationship instead.

Be sure to support your postings and responses with specific references to the Learning Resources.

Application: Strengths and Limitations of Correlational Design

Correlational designs have been used in all areas of research. Forensic psychology research is no exception. As you have seen from your readings, many phenomena do not lend themselves to true experimental design. For example, an experimental research study that looks at the effect of viewing violent content, either on television or in video games, would be more challenging, both practically and ethically, than a similar study using a correlational design. Correlational research designs allow researchers to study behavior as it occurs naturally. However, to do so probably would compromise the ability to draw cause-and-effect conclusions.

To prepare for this assignment:

• Review Chapter 9 in your course text, Research Methods for the Behavioral Sciences. Consider the strengths and limitations of using correlational data, in general, and as it relates to research in forensic psychology or in forensic settings.

• Review the article, "Forensic Psychology: An Empirical Review of Experimental Research." Focus on the strengths and limitations of empirical and correlational design.

• Using the Walden Library, select and review two research articles covering different topic areas, both of which use a correlational design.

• Think about the strengths and limitations of the correlational design used in each of the two research articles you chose.

The assignment (1-3 pages):

• Briefly describe each of the studies in the two research articles you selected. Include a description of the results of the studies and the correlational relationship reported.

• Explain the strengths and limitations of using a correlational design in each of the studies.

Support your Application Assignment with specific references to all resources used in its preparation. You are asked to provide a reference list only for those resources not included in the Learning Resources for this course.